How to Calculate Age from Two Dates in Excel

What this does

DATEDIF measures the gap between a start date and an end date in the unit you ask for. With the birth date as the start, TODAY() as the end and "Y" as the unit, it returns the number of full years lived — the person's current age. Swap the unit to "M" for whole months or "D" for total days. DATEDIF is hidden from the function list but works in every Excel version and in Google Sheets. The same idea underpins a lot of everyday Excel work, so the few minutes spent getting it right here pay back across every sheet you build afterwards. Treat it as a pattern, not a one-off, and it stops being something you look up and starts being something you reach for. Treat “calculate age from two dates in excel” as a small repeatable workflow rather than a one-off click you hope to remember next time. Use a small test block before the live file, so any surprise in the affected cells shows up while it is still harmless. When a formula is involved, keep the inputs labelled beside it, reference cells instead of typing values, and apply number formatting only after the result checks out. That turns a calculation you can defend to a CFO or an auditor into a method you can reuse, explain, and defend when the workbook leaves your screen.

A worked example

A2 holds the birth date 1990-06-15. In B2 type =DATEDIF(A2,TODAY(),"Y"). With today around 2026 the result is 35, because the person has completed 35 birthdays. You reach for DATEDIF whenever a report needs a live age from a birth date — staff records, customer profiles, eligibility checks — that recalculates as time passes. A practical tip before you scale it up: build it once on a small block of test data, confirm the number against the tool on this page, and only then point it at your real sheet. That one habit catches almost every mistake while it is still cheap to fix, long before a wrong figure reaches a report or a colleague.

In Google Sheets

Everything above works in Google Sheets too. Excel and Sheets share the formula syntax used here; only the surrounding menus are arranged differently. That portability is deliberate — learn it once and it follows you between the two tools and across Windows and Mac. The aim was to get you unstuck fast and leave you a little more capable than a copy-paste would. The answer is at the top, the tool proves it, and the detail above shows why it holds — so the next time a colleague asks, you can answer without reaching for search. The short version of “calculate age from two dates in excel”: the answer is at the top of this page, the tool proves it on your own numbers, and the sections above explain why it holds so the next variation does not stump you. Excel rewards people who reference cells instead of typing values and who keep inputs separate from formulas, because that is what makes a result you can audit months later. Build it once, deliberately, with the live tool as a check, and you convert a one-off lookup into a reusable skill — which is the whole point of learning the why and not just the what.

Common mistakes

• Formatting the result as a date, so 35 shows as a date instead of a number.
• Using "Y" when you actually wanted months or days.
• Putting the dates in the wrong order — start must be earlier than end or DATEDIF errors.
• Hard-coding today's date instead of TODAY(), so the age never updates.

Frequently asked questions